Mammary tubulopapillary carcinoma in a mare, requiring bilateral mastectomy.

Abstract

Mammary neoplasia is uncommon in the mare and often mistaken for mastitis (Reppas et al. Citation1996). Incidence rates of mammary tumours in horses of 0.1–1.9% are reported, with carcinomas the most common (Brito et al. Citation2008). Due to the low incidence, and similarity of initial signs to those of mastitis, diagnosis is often delayed until after antibiotic and anti-inflammatory treatment has failed (Boyce and Goodwin Citation2017). Mares are often, therefore, presented in an advanced stage of disease with a poor prognosis (Ferreira Júnior et al. Citation2019). Due to the infrequency of mammary neoplasia in horses it has been difficult to develop an evidence based approach to treatment. Studies in domestic animals report a low success rate with conservative management of these neoplasms. Combined with their highly aggressive and metastatic nature, surgical excision has been perceived as the treatment of choice in the initial management of these neoplasms (Seahorn et al. Citation1992).